This invention relates to a support structure for highway signs, or other similar roadside fixtures. More particularly, the present invention relates to a breakaway coupling to be interposed in a portion of a support structure that allows severing of a first portion of the support structure from a second portion of the support structure upon an impact.
There are many support post structures erected along highways for holding up signs, lights, and other objects. It is desirable to have the support structures for many of these items breakable upon impact with a vehicle on the highway. By making support structures breakable upon impact, the amount of damage to the vehicle and its occupants upon impact is reduced. In the past, support structures were provided with some type of breakaway feature which allows the support structure to break off or bend away when hit by a vehicle with a predetermined impact force.
Some devices required shearing of the support structure itself at a weakened portion or the shearing of other members such as shear pins. While this type of breakaway feature eliminates certain hazards, unfortunately, such resistance to breaking or bending caused the impact to do substantial damage to the vehicle with possible serious injuries to the occupants of the vehicle. Additionally, the impact often destroyed the support structure so that complete replacement was necessary. It is therefore desirable to provide an improved way to break away a support structure upon impact with a vehicle to minimize damage to the vehicle and the occupants and to permit re-use of portions of the support structure.
The present invention, according to one embodiment is directed to a breakaway coupling for a support structure having a first portion and a second portion. The breakaway coupling has a first mounting member. The first mounting member is mountable to the first portion of the support structure. A first plate is coupled to the first mounting member and a second plate is breakably coupled to the first plate. A second mounting member is coupled to the second plate; the second mounting member being mountable to the second portion of the support structure. A bearing is positioned between the first plate and the second plate.
In one embodiment, the bearing has a bearing housing, which includes a first bearing retainer layer positioned adjacent to the first plate, a second bearing retainer layer positioned adjacent to the second plate, and a third bearing retainer layer positioned between the first bearing retainer layer and the second bearing retainer layer. The first bearing retainer layer, the second bearing retainer layer and the third bearing retainer layer can be all made of polypropylene. At least one of the first plate, the second plate, the first bearing retainer layer, the second bearing retainer layer and the third bearing retainer layer may be hexagonally shaped. The bearing may include a plurality of ball bearings positioned inside of the bearing housing. In one embodiment, the bearing has six ball bearings. The bearings may be made of steel.
In one embodiment, the first mounting member is welded to the first plate and the second mounting member is welded to the second plate. The first plate may be breakably coupled to the second plate by a plurality of nuts and bolts. The first mounting member having a plurality of holes is coupled to the first portion of the support structure using at least one bolt passed through at least one of the plurality of holes in the first mounting member. Likewise, the second mounting member comprises a plurality of holes and is coupled to the second portion of the support structure using at least one bolt passed through at least one of the plurality of holes in the second mounting member.